Helicobacter pylori is a pathogenic bacterium discovered in 1983, which is regarded as the cause of diseases at the upper digestive organs, such as peptic ulcers (e.g., gastric and duodenal ulcers), inflammations (e.g., gastritis) and gastric cancer, and of MALT (mucosa-associated lymphoid tissue) lymphoma or as a background pathogenic factor of chronic heart diseases. Studies on the treatment of Helicobacter pylori infection are active now, and a large number of therapeutic methods have been reported, including those for removing the bacterium or those for preventing relapse, as described below. The examples include a single agent administration method using bismuth, an antibiotic, a proton pump inhibitor (PPI), an antitumor agent, or the like and a multiple agent combination method (two agent combination or three agent combination) which uses a combination of these agents, etc. ("Internal Medicine", Special Edition, vol. 78, no. 1 (1996), published by Nankodo). However, these therapeutic methods have many problems to be solved, such as high frequency of administration times, requirement of administration in a dose larger than the usual dose in some cases, onset of diarrhea or constipation caused by the drug administration and generation of resistant strains.
The compound related to the present invention as a substance useful as an anti-Helicobacter pylori pharmaceutical composition, is disclosed in JP-A-7-189 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") as a substance YL-02729S, and its use is particularly antibacterial activity upon methicillin-resistant Staphylococcus aureus. Said patent application does not suggest or report about antibacterial activity of the substance YL-02729S upon Helicobacter pylori.